What is it about?

The transfer of electrons when molecules and metal surfaces interact is central to many processes. Determining the charge transfer states is a unique challenge with these processes. First principles methods are used to determine these states. But these conventional methods are unreliable. The authors of this study propose a practical system for studying this phenomenon. They used another approach called the “constrained density functional theory” (CDFT) as the first principles method to check if it can be used to assess charge transfer states. The authors observed that it was easier to compute the charge constraint on a molecule using the widely used method called “Bader’s charge analysis.” This method helped identify all possible charge transfer states. The proposed system was then used to predict the states for four benchmark systems. Interestingly, the study found that electron transfer depends on the work function of the metal and the electron affinity of each molecule. Thus, the authors suggest that the CDFT system is a simple yet efficient method for computing the charge transfer states in metal surfaces.

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Why is it important?

The interaction between a molecule and metal surface is important for many chemical processes. We need to understand the transfer of electrons to study electron scattering processes. Conventional models based on first principles are used to study electron transfer, but these have high computational costs and poor accuracy. Also, these are inapplicable to a metal surface with a continuum of states. The practical CDFT scheme proposed here can produce precise potential energy surfaces. With this we can study the nonadiabatic molecular dynamics on metal surfaces. We can use it to study other interfacial electron transfer processes as well. KEY TAKEAWAY: The proposed model predicts the electron transfer behavior between a molecule and a metal surface. It uses the CDFT scheme to study diabatic states. It can help to shed light on an enduring problem in surface chemistry.

Read the Original

This page is a summary of: A pragmatic protocol for determining charge transfer states of molecules at metal surfaces by constrained density functional theory, The Journal of Chemical Physics, December 2022, American Institute of Physics,
DOI: 10.1063/5.0124054.
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